How long does 1 GB last? Estimating data for Japan and Korea

Official figures

Japanese carrier au (updated April 2026): 1 GB is about 1.5 hours of YouTube at 720p, or about 40 hours of LINE voice calls or 3 hours of video calls.

Netflix: on a phone, “Automatic” quality is about 4 hours per GB and “Save Data” about 6 hours.

Spotify: the highest quality is 320 kbit/s, about 144 MB an hour.

Zoom: voice uses 60 to 80 kbit/s; a one-to-one HD video call about 600 kbit/s each way.

Web pages: the median mobile page is about 2 to 2.6 MB (HTTP Archive, 2025).

Maps and social apps: check your own phone

There are no official figures for Google Maps, Instagram or TikTok, and published estimates differ tenfold. Your phone's per-app usage for the last month is the best guide; see how much data to buy.

What still works after the speed drops

Many plans slow down once the high-speed allowance is used. Working from the official figures above: 128 kbps handles text messages and voice calls, but a 2 MB page takes about two minutes to load; 1 Mbps handles a one-to-one video call, and video only up to 360p; 5 Mbps meets YouTube's recommended speed for 1080p.

Each plan's remaining speed is under “After the allowance” in its details.

What uses the most on a trip

Automatic photo and video backup uses the most. Turn off cellular backup for iCloud Photos or Google Photos while travelling and upload on hotel Wi-Fi.

iPhone's Low Data Mode pauses automatic updates, background tasks and photo syncing. If you share a hotspot with a laptop, its system updates and cloud sync also use the eSIM's data.

Example: 7 days in Japan

Thirty minutes of YouTube at 720p on the train each day comes to about 2.3 GB over 7 days for the video alone. Add your other usage from your phone's history and pick a Japan eSIM at or just above the total.